Question

solve it please*.......​

Answer 1

Answer:

option (d) 90cm is correct

Explanation:

to calculate position of image formed due to convex lense

1/v - /u =1/f

1/v - 1/-30=1/20

1/v=1/20-1/30=3-2/60=1/60

v = 60 cm

so, image formed by convex lense is at 60 cm from lense or 30 cm from the mirror image is formed at radius of curvature of mirror if mirror was not there.

As we can see from the ray diagrams , ray fall along the normal to the mirror.

So, rays retrace their path.

final image is formed at objects positions only final image I2O coincides with initial position of object. Distance between I1 and I2 is 90 cm.

Note:- that if we solve for second image using mirror formula treating I1 as object for mirror , we will get the final image at I2 only but it is the virtual image , there will be another refraction through lens and that becomes clear if we draw the ray diagrams.

Answer 2

$\huge\bigstar\underline\pink{Answer}$

$\boxed{refer\:to\: attachment}$

We have lens equation (1/v) - (1/u) = 1/f

where u id lens-to-object distance, v is lens-to-image distance and f is focal length

if we use u = -30 cm and f = 20 cm in lens equation, we get image distance from lens as follows

(1/v) - (1/-30) = 1/20 or (1/v) = ( 1/20 ) - (1/30) = 1/60 or v = 60 cm.

Due to reflection at convex mirror, image I1 is formed at a distance 30 cm in front of mirror,

because mirror is placed at a distance 30 cm from lens.

Image formed at I1 acts as virtual object to concave mirror.

We have mirror equation (1/v)+(1/u) = 1/f .

since 30 cm is radius of curvature for mirror, focal length is 15 cm

1/v = 1/15 - (1/30) = 1/30 or v = 30 cm

Image I2 is formed at a distance 30 cm from pole of mirror.

Distance between Images is 30+30 = 60 cm.

✔️✔️$\boxed{option\:one\:is\: correct}$